The Rockies didn’t have a snowball’s chance in Hades against the Mariners Saturday night at frigid Coors Field.

Not with right-hander Luis Castillo baffling hitters for seven splendid innings and Colorado’s defense taking the night off with right fielder Sean Bouchard and center fielder Brenton Doyle both committing sloppy errors. First baseman Elehuris Montero was initially charged with another error, but the ruling was reversed after the game.

For the record, Seattle blanked the Rockies, 7-0, sending them to their sixth consecutive loss. It was Colorado’s fourth shutout this season. The Rockies’ 4-16 record is the worst over the first 20 games in franchise history. For some sobering perspective, the infamously bad 1962 Mets were also 4-16 in their inaugural season.

Castillo pitched seven scoreless innings, striking out nine and walking one. He allowed just two hits — a two-out single by Elias Diaz in the fourth and a fluke two-out single by Bouchard in the fifth. Bouchard popped the ball up to first baseman Ty France, but France lost the ball in a flurry of snowflakes.

It was a case of déjà vu for Castillo, who extended his scoreless streak against the Rockies to 14 innings. On April 16 of last season, he carried a perfect game into the seventh allowing two hits and striking out nine batters over seven innings in the Mariners’ 1-0 victory in Seattle.

Rockies starter Dakota Hudson deserved a little better fate than what he was handed. But only a little. After all, he issued five walks in his four-plus innings. He gave up four runs (three earned) on six hits.

Seattle’s four-run fifth was an epic disaster for the Rockies and clinched the game.

It began with Cal Raleigh drawing a leadoff walk off of Hudson, who got the hook from manager Bud Black. In came Victor Vodnik, who was unscored upon in 12 1/3 innings entering the night. He was greeted by back-to-back singles by Ty France and Mitch Garver, loading the bases. Then came Bouchard’s miscue. Jonatan Clase skidded a single into right field and Bouchard let the ball go under his glove as three runs scored. Clase almost had a Little League homer but was thrown out at the plate.

Raleigh, who had a career-high four hits, led off the second with a homer to left and added an RBI single in the third to put Seattle up 2-0.

Montero mistake opened the door for another Seattle run in the fourth. Montero’s drifted much too far off first to field J.P. Crawford’s grounder, leaving no one to cover the bag. Sure enough, Julio Rodriguez followed with a two-out RBI single to score Josh Rojas and gave Seattle a 3-0 lead.